Add mkmap.sh-example that shoud be run by cron (#89)

README.md

@@ -10,11 +10,19 @@ ffmap-backend gathers information on the batman network by invoking :
 
 The output will be written to a directory (`-d output`).
 
-Run `backend.py --help` for a quick overview of all available options.
+Copy `mkmap.sh-example` to `mkmap.sh` and adapt to your needs, test `backend.py` for example with: 
+
+    backend.py -d /path/to/output -a /path/to/aliases.json --vpn ae:7f:58:7d:6c:2a d2:d0:93:63:f7:da
 
-For the script's regular execution add the following to the crontab:
+Run `backend.py --help` for a quick overview of all available options.
 
-    * * * * * backend.py -d /path/to/output -a /path/to/aliases.json --vpn ae:7f:58:7d:6c:2a --vpn d2:d0:93:63:f7:da
+For the script's regular execution add the following file to cron in `/etc/cron.d/ffmap-backend`:
+
+    [email protected]
+    # Freifunk Map Updates
+    PATH=/usr/sbin:/usr/bin:/sbin:/bin
+    * * * * *       root nice -n 19 /path/to/mkmap.sh > /dev/null 2>&1
+    # EOF
 
 # Dependencies
 

mkmap.sh-example

@@ -0,0 +1,22 @@
+#!/bin/bash
+MAXLOAD=2 # don't run when load is equal or bigger than 2.0
+FFMAPPATH='/opt/ffmap-backend'
+TMPPATH='/tmp/ffmap-backend'
+TLD=ffgc
+
+if [ $(pgrep -c $(basename $0)) -gt 1 ]; then 
+  echo $(basename $0) is already running
+  exit 0
+fi
+
+load=`grep -o "^." /proc/loadavg`
+if [ "$load" -gt $MAXLOAD ]; then
+  exit 1
+fi
+
+mkdir -p $TMPPATH
+cd $FFMAPPATH
+cp json/nodes.json $TMPPATH/
+python3 $FFMAPPATH/backend.py -d /$TMPPATH/ --aliases $FFMAPPATH/gateway.json -m bat-$TLD:/var/run/alfred.bat-$TLD.sock -p 62 --vpn de:ad:be:ef:ff:01 de:ad:be:ff:ff:02
+cp /$TMPPATH/* /$FFMAPPATH/json/
+